Editing Flash memory (section)

==Distinction between NOR and NAND flash==
NOR and NAND flash differ in two important ways:
* The connections of the individual memory cells are different.<ref>{{Cite book|url=https://books.google.com/books?id=vaq11vKwo_kC&dq=nor+flash+nand+flash&pg=PA3|title=Inside NAND Flash Memories|first1=Rino|last1=Micheloni|first2=Luca|last2=Crippa|first3=Alessia|last3=Marelli|date=27 July 2010|publisher=Springer Science & Business Media|isbn=9789048194315 |via=Google Books}}</ref>
* The interface provided for reading and writing the memory is different; NOR allows [[random access]]<ref>{{cite book | url=https://books.google.com/books?id=abfBAAAAQBAJ&dq=nor+random+access&pg=PA35 | title=Flash Memories: Economic Principles of Performance, Cost and Reliability Optimization | isbn=978-94-007-6082-0 | last1=Richter | first1=Detlev | date=12 September 2013 | publisher=Springer }}</ref> as it can be either byte-addressable or word-addressable, with words being for example 32 bits long,<ref name="factsonfile">{{Cite book |last1=Daintith |first1=John |last2=Wright |first2=Edmund |url=https://books.google.com/books?id=9Q9XNh716ikC&dq=nor+byte+addressable&pg=PA123 |title=The Facts on File Dictionary of Computer Science |date=14 May 2014 |publisher=Infobase Publishing |isbn=9781438109398 |via=Google Books }}</ref><ref>{{Cite book|url=https://books.google.com/books?id=VDkPEAAAQBAJ&dq=nor+byte+addressable&pg=PR22|title=Silicon Based Unified Memory Devices and Technology|first=Arup|last=Bhattacharyya|date=6 July 2017|publisher=CRC Press|isbn=9781351798327 |via=Google Books}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=rGjkBQAAQBAJ&dq=nor+random+access+byte+addressable&pg=PA59|title=FUNDAMENTALS OF COMPUTERS|first1=V.|last1=RAJARAMAN|first2=NEEHARIKA|last2=ADABALA|date=15 December 2014|publisher=PHI Learning Pvt. Ltd.|isbn=9788120350670 |via=Google Books}}</ref> while NAND allows only page access.<ref>{{cite web|last=Aravindan|first=Avinash|date=2018-07-23|title=Flash 101: NAND Flash vs NOR Flash|url=https://www.embedded.com/flash-101-nand-flash-vs-nor-flash/|access-date=2020-12-23|website=Embedded.com|language=en-US}}</ref>

NOR<ref>{{cite book | url=https://books.google.com/books?id=7XhhDwAAQBAJ&dq=nor+random+access&pg=PA113 | title=Bits on Chips | isbn=978-3-319-76096-4 | last1=Veendrick | first1=Harry | date=21 June 2018 | publisher=Springer }}</ref> and NAND flash get their names from the structure of the interconnections between memory cells.<ref>{{Cite web |title=NAND and NOR Gates |url=https://bob.cs.sonoma.edu/testing/sec-nand.html |access-date=2024-11-03 |website=bob.cs.sonoma.edu}}</ref> In NOR&nbsp;flash, cells are connected in parallel to the bit lines, allowing cells to be read and programmed individually.<ref name="auto7">{{Cite book|url=https://books.google.com/books?id=vaq11vKwo_kC&dq=nand+flash+xip&pg=PA12|title=Inside NAND Flash Memories|first1=Rino|last1=Micheloni|first2=Luca|last2=Crippa|first3=Alessia|last3=Marelli|date=27 July 2010|publisher=Springer Science & Business Media|isbn=9789048194315 |via=Google Books}}</ref> The parallel connection of cells resembles the parallel connection of transistors in a CMOS NOR gate.<ref>{{Cite book|url=https://books.google.com/books?id=44mbEAAAQBAJ&dq=nor+flash+nor+gate&pg=PA55|title=Springer Handbook of Semiconductor Devices|first1=Massimo|last1=Rudan|first2=Rossella|last2=Brunetti|first3=Susanna|last3=Reggiani|date=10 November 2022|publisher=Springer Nature|isbn=9783030798277 |via=Google Books}}</ref> In NAND&nbsp;flash, cells are connected in series,<ref name="auto7"/>  resembling a CMOS NAND gate. The series connections consume less space than parallel ones, reducing the cost of NAND&nbsp;flash.<ref name="auto7"/>  It does not, by itself, prevent NAND cells from being read and programmed individually.{{Citation needed|date=September 2020}}

Each NOR flash cell is larger than a NAND&nbsp;flash cell{{snd}} 10&nbsp;F<sup>2</sup> vs 4&nbsp;F<sup>2</sup>{{snd}}{{vague|date=October 2024}} even when using exactly the same [[semiconductor device fabrication]] and so each transistor, contact, etc. is exactly the same size{{snd}} because NOR&nbsp;flash cells require a separate metal contact for each cell.<ref>{{Citation |publisher=Micron |url=http://www.micron.com/~/media/Documents/Products/Technical%20Note/NAND%20Flash/tn2919_nand_101.pdf |id=TN-29-19 |title=NAND Flash 101: An Introduction to NAND Flash and How to Design It in to Your Next Product |pages=2–3 |url-status=dead |archive-url=https://web.archive.org/web/20160604054353/https://www.micron.com/~/media/Documents/Products/Technical%20Note/NAND%20Flash/tn2919_nand_101.pdf |archive-date=4 June 2016}}</ref><ref>{{cite book | url=https://books.google.com/books?id=2E0r6BRo2VkC&dq=nor+flash+nand+flash&pg=PA200 | title=CMOS Processors and Memories | isbn=978-90-481-9216-8 | last1=Iniewski | first1=Krzysztof | date=9 August 2010 | publisher=Springer }}</ref>

Because of the series connection and removal of wordline contacts, a large grid of NAND&nbsp;flash memory cells will occupy perhaps only 60% of the area of equivalent NOR cells<ref name="flash_overview">{{Cite news |last1=Pavan |first1=Paolo |last2=Bez |first2=Roberto |last3=Olivo |first3=Piero |last4=Zanoni |first4=Enrico |publication-date=August 1997 |title=Flash Memory Cells – An Overview |periodical=Proceedings of the IEEE |volume=85 |issue=8 |pages=1248–1271 |url= https://ieeexplore.ieee.org/document/622505 |access-date=15 August 2008 |doi=10.1109/5.622505 |year=1997}}</ref> (assuming the same [[CMOS]] process resolution, for example, 130&nbsp;[[nanometer|nm]], 90&nbsp;nm, or 65&nbsp;nm). NAND&nbsp;flash's designers realized that the area of a NAND chip, and thus the cost, could be further reduced by removing the external address and data bus circuitry. Instead, external devices could communicate with NAND&nbsp;flash via sequential-accessed command and data registers, which would internally retrieve and output the necessary data. This design choice made random-access of NAND&nbsp;flash memory impossible, but the goal of NAND&nbsp;flash was to replace mechanical [[hard disk]]s, not to replace ROMs. 

The first [[GSM]] phones and many [[feature phone]]s had NOR flash memory, from which processor instructions could be executed directly in an execute-in-place architecture and allowed for short boot times. With smartphones, NAND flash memory was adopted as it has larger storage capacities and lower costs, but causes longer boot times because instructions cannot be executed from it directly, and must be copied to RAM memory first before execution.<ref>{{cite book | url=https://books.google.com/books?id=vaq11vKwo_kC&dq=nand+flash+copy+sram&pg=PA12 | title=Inside NAND Flash Memories | isbn=978-90-481-9431-5 | last1=Micheloni | first1=Rino | last2=Crippa | first2=Luca | last3=Marelli | first3=Alessia | date=27 July 2010 | publisher=Springer }}</ref>

{| class="wikitable"
|-
! Attribute !! NAND !! NOR
|-
| Main application || File storage || Code execution
|-
| Storage capacity || Higher || Lower
|-
| Cost per bit || Lower || Higher
|-
| Active power || Lower || Higher
|-
| Standby power || Higher || Lower
|-
| Write speed || Faster || Slower
|-
| Random read speed || Slower || Faster
|-
| [[Execute in place]]<ref>{{cite book | url=https://books.google.com/books?id=WLg85jlQaIAC&dq=nor+flash+random+access+xip&pg=PA253 | title=Computational Science and Its Applications - ICCSA 2007: International Conference, Kuala Lumpur, Malaysia, August 26-29, 2007. Proceedings, Part I | isbn=978-3-540-74472-6 | last1=Gervasi | first1=Osvaldo | date=29 August 2007 | publisher=Springer }}</ref> (XIP) || No || Yes
|-
| Reliability || Lower || Higher
|}

===Write endurance===
The write endurance of SLC floating-gate NOR flash is typically equal to or greater than that of NAND&nbsp;flash, while MLC&nbsp;NOR and NAND&nbsp;flash have similar endurance capabilities. Examples of endurance cycle ratings listed in datasheets for NAND and NOR&nbsp;flash, as well as in storage devices using flash memory, are provided.<ref>{{cite web |url=http://electronicdesign.com/memory/fundamentals-flash-memory-storage |title=The Fundamentals of Flash Memory Storage |access-date=2017-01-03 |url-status=live |archive-url=https://web.archive.org/web/20170104163357/http://electronicdesign.com/memory/fundamentals-flash-memory-storage |archive-date=4 January 2017|date=2012-03-20 }}</ref>

{| class="wikitable sortable"
|-
! Type of flash<br>memory !! Endurance rating<br>(erases per [[Block (data storage)|block]]) !! Example(s) of flash memory or storage device
|-
| [[Single-level cell|SLC]] NAND || 50,000–100,000 || Samsung OneNAND KFW4G16Q2M, Toshiba SLC NAND flash chips,<ref name="auto">{{cite web|url=https://business.toshiba-memory.com/en-emea/product/memory/slc-nand/slc.html|title=SLC NAND Flash Memory &#124; TOSHIBA MEMORY &#124; Europe(EMEA)|website=business.toshiba-memory.com|access-date=1 January 2019|archive-date=1 January 2019|archive-url=https://web.archive.org/web/20190101193808/https://business.toshiba-memory.com/en-emea/product/memory/slc-nand/slc.html|url-status=dead}}</ref><ref>{{cite web|url=https://www.toshiba.com/tma/technologymoves/slc-nand.jsp|title=SLC NAND |website=Toshiba.com |archive-url=https://web.archive.org/web/20180901074546/https://www.toshiba.com/tma/technologymoves/slc-nand.jsp |archive-date=1 September 2018 |url-status=dead }}</ref><ref>{{cite web|url=https://business.toshiba-memory.com/en-emea/product/memory/slc-nand/serial.html|title=Serial Interface NAND &#124; TOSHIBA MEMORY &#124; Europe(EMEA)|website=business.toshiba-memory.com|access-date=1 January 2019|archive-date=1 January 2019|archive-url=https://web.archive.org/web/20190101145411/https://business.toshiba-memory.com/en-emea/product/memory/slc-nand/serial.html|url-status=dead}}</ref><ref>{{cite web|url=https://business.toshiba-memory.com/en-emea/product/memory/slc-nand/benand.html|title=BENAND &#124; TOSHIBA MEMORY &#124; Europe(EMEA)|website=business.toshiba-memory.com|access-date=1 January 2019|archive-date=1 January 2019|archive-url=https://web.archive.org/web/20190101145413/https://business.toshiba-memory.com/en-emea/product/memory/slc-nand/benand.html|url-status=dead}}</ref><ref>{{cite web|url=https://business.toshiba-memory.com/en-emea/product/memory/slc-nand.html|title=SLC NAND Flash Memory &#124; TOSHIBA MEMORY &#124; Europe(EMEA)|website=business.toshiba-memory.com|access-date=1 January 2019|archive-date=1 January 2019|archive-url=https://web.archive.org/web/20190101145415/https://business.toshiba-memory.com/en-emea/product/memory/slc-nand.html|url-status=dead}}</ref> Transcend SD500, Fujitsu S26361-F3298
|-
| [[Multi-level cell|MLC]] NAND || 5,000–10,000 for<br>medium-capacity;<br />1,000 to 3,000 for<br>high-capacity<ref name="auto4">{{cite web|url=https://arstechnica.com/gadgets/2019/09/new-intel-toshiba-ssd-technologies-squeeze-more-bits-into-each-cell/|title=SSDs are on track to get bigger and cheaper thanks to PLC technology|first=Jim|last=Salter|date=28 September 2019|website=Ars Technica}}</ref> || Samsung K9G8G08U0M (example for medium-capacity applications), Memblaze PBlaze4,<ref>{{cite web|url=http://memblaze.com/en/index.php?c=article&a=type&tid=54|title=PBlaze4_Memblaze|website=memblaze.com|access-date=2019-03-28}}</ref> ADATA SU900, Mushkin Reactor
|-
| TLC NAND || 1,000 || Samsung SSD 840
|-
| QLC NAND || {{unknown}} || SanDisk X4 NAND flash SD cards<ref>{{cite web|url=https://www.cnet.com/news/sandisk-to-begin-making-x4-flash-chips/|title=SanDisk to begin making 'X4' flash chips|first=Brooke|last=Crothers|website=CNET}}</ref><ref>{{cite web|url=https://www.cnet.com/news/sandisk-ships-x4-flash-chips/|title=SanDisk ships 'X4' flash chips|first=Brooke|last=Crothers|website=CNET}}</ref><ref>{{cite web|url=https://phys.org/news/2009-10-sandisk-ships-memory-cards-gigabit.html|title=SanDisk Ships Flash Memory Cards With 64 Gigabit X4 NAND Technology|website=phys.org}}</ref><ref>{{cite web|url=https://www.photoreview.com.au/news/sandisk-begins-mass-production-of-x4-flash-memory-chips/|title=SanDisk Begins Mass Production of X4 Flash Memory Chips|date=17 February 2012}}</ref>
|-
| 3D SLC NAND || >100,000 || Samsung Z-NAND<ref name="auto2">{{cite web|url=https://www.anandtech.com/show/13951/the-samsung-983-zet-znand-ssd-review|title=The Samsung 983 ZET (Z-NAND) SSD Review: How Fast Can Flash Memory Get?|first=Billy|last=Tallis|website=AnandTech.com}}</ref>
|-
| {{nowrap|3D MLC NAND}} || 6,000–40,000 || Samsung SSD 850 PRO, Samsung SSD 845DC PRO,<ref name="AnandTech-SSD850PROEndurance">{{cite web|last1=Vättö|first1=Kristian|title=Testing Samsung 850 Pro Endurance & Measuring V-NAND Die Size|url=http://www.anandtech.com/show/8239/update-on-samsung-850-pro-endurance-vnand-die-size|website=[[AnandTech]]|access-date=11 June 2017|url-status=live|archive-url=https://web.archive.org/web/20170626155736/http://www.anandtech.com/show/8239/update-on-samsung-850-pro-endurance-vnand-die-size|archive-date=26 June 2017}}</ref><ref name="AnandTech-SamsungSSD845DCPreview-p3">{{cite web|last1=Vättö|first1=Kristian|title=Samsung SSD 845DC EVO/PRO Performance Preview & Exploring IOPS Consistency|url=http://www.anandtech.com/show/8319/samsung-ssd-845dc-evopro-preview-exploring-worstcase-iops/3|website=[[AnandTech]]|access-date=11 June 2017|page=3|url-status=live|archive-url=https://web.archive.org/web/20161022231209/http://www.anandtech.com/show/8319/samsung-ssd-845dc-evopro-preview-exploring-worstcase-iops/3|archive-date=22 October 2016}}</ref> Samsung 860 PRO
|-
| 3D TLC NAND || 1,500–5,000 || Samsung SSD 850 EVO, Samsung SSD 845DC EVO, Crucial MX300<ref name="AnandTech-SamsungSSD850EVOReview-p4">{{cite web|last1=Vättö|first1=Kristian|title=Samsung SSD 850 EVO (120GB, 250GB, 500GB & 1TB) Review|url=http://www.anandtech.com/show/8747/samsung-ssd-850-evo-review/4|website=[[AnandTech]]|access-date=11 June 2017|page=4|url-status=live|archive-url=https://web.archive.org/web/20170531043312/http://www.anandtech.com/show/8747/samsung-ssd-850-evo-review/4|archive-date=31 May 2017}}</ref><ref name="AnandTech-SamsungSSD845DCPreview-p2">{{cite web|last1=Vättö|first1=Kristian|title=Samsung SSD 845DC EVO/PRO Performance Preview & Exploring IOPS Consistency|url=http://www.anandtech.com/show/8319/samsung-ssd-845dc-evopro-preview-exploring-worstcase-iops/3|website=[[AnandTech]]|access-date=11 June 2017|page=2|url-status=live|archive-url=https://web.archive.org/web/20161022231209/http://www.anandtech.com/show/8319/samsung-ssd-845dc-evopro-preview-exploring-worstcase-iops/3|archive-date=22 October 2016}}</ref><ref name="Toms-FlashIndustryTrends">{{Cite news |date=9 June 2017 |title=Flash Industry Trends Could Lead Users Back to Spinning Disks |work=[[Tom's Hardware]] |url=https://www.tomshardware.com/news/consumer-optane-enterprise-ssd-market,34631.html |url-status=live |access-date=11 June 2017 |archive-url=https://web.archive.org/web/20231106202840/https://www.tomshardware.com/news/consumer-optane-enterprise-ssd-market,34631.html |archive-date=6 November 2023 |last1=Ramseyer |first1=Chris }}</ref>，Memblaze PBlaze5 900, Memblaze PBlaze5 700, Memblaze PBlaze5 910/916, Memblaze PBlaze5 510/516,<ref name="memblaze-pblaze5-700">{{Cite web |title=PBlaze5 700 |url=http://memblaze.com/en/index.php?c=article&a=type&tid=100 |url-status=dead |archive-url=https://web.archive.org/web/20190328104601/http://memblaze.com/en/index.php?c=article&a=type&tid=100 |archive-date=28 March 2019 |access-date=28 March 2019 |website=memblaze.com }}</ref><ref name="memblaze-pblaze5-900">{{Cite web |title=PBlaze5 900 |url=http://memblaze.com/en/index.php?c=article&a=type&tid=101 |url-status=dead |archive-url=https://web.archive.org/web/20190328104342/http://memblaze.com/en/index.php?c=article&a=type&tid=101 |archive-date=28 March 2019 |access-date=28 March 2019 |website=memblaze.com }}</ref><ref name="memblaze-pblaze5-910">{{Cite web |title=PBlaze5 910/916 series NVMe SSD |url=http://memblaze.com/en/index.php?c=article&a=type&tid=102 |url-status=dead |archive-url=https://web.archive.org/web/20190327091248/https://memblaze.com/en/index.php?c=article&a=type&tid=102 |archive-date=27 March 2019 |access-date=26 March 2019 |website=memblaze.com }}</ref><ref name="memblaze-pblaze5-510">{{Cite web |title=PBlaze5 510/516 series NVMe™ SSD |url=http://memblaze.com/en/index.php?c=article&a=type&tid=103 |url-status=dead |archive-url=https://web.archive.org/web/20190327091116/http://memblaze.com/en/index.php?c=article&a=type&tid=103 |archive-date=27 March 2019 |access-date=26 March 2019 |website=memblaze.com }}</ref> ADATA SX 8200 PRO (also being sold under "XPG Gammix" branding, model S11 PRO)
|-
| 3D QLC NAND || 100–1,500 ||  Samsung SSD 860 QVO SATA, Intel SSD 660p, Micron 5210 ION, Crucial P1, Samsung SSD BM991 NVMe<ref name="evans-qlc-nand">{{Cite web |last=Evans |first=Chris |date=7 November 2018 |title=QLC NAND - What can we expect from the technology? |url=https://www.architecting.it/blog/qlc-nand/ |url-status=live |archive-url=https://web.archive.org/web/20231102133726/https://www.architecting.it/blog/qlc-nand/ |archive-date=2 November 2023 }}</ref><ref name="micron-20181105">{{Cite press release |last=Dicker |first=Derek |date=5 November 2018 |title=Say Hello: Meet the World's First QLC SSD, the Micron 5210 ION |url=https://www.micron.com/about/blog/2018/november/meet%20the%20worlds%20first%20qlc%20ssd%20the%20micron%205210%20ion |url-status=live |archive-url=https://web.archive.org/web/20190130163245/https://www.micron.com/about/blog/2018/november/meet%20the%20worlds%20first%20qlc%20ssd%20the%20micron%205210%20ion |archive-date=30 January 2019 |publisher=[[Micron Technology]] }}</ref><ref>{{cite web|url=https://www.micron.com/products/advanced%20solutions/qlc%20nand|archive-url=https://web.archive.org/web/20190130091405/https://www.micron.com/products/advanced%20solutions/qlc%20nand|url-status=dead|archive-date=30 January 2019|title=QLC NAND|website=Micron.com}}</ref><ref name="anandtech-20180807">{{Cite news |last=Tallis |first=Billy |title=The Intel SSD 660p SSD Review: QLC NAND Arrives For Consumer SSDs |work=[[AnandTech]] |url=https://www.anandtech.com/show/13078/the-intel-ssd-660p-ssd-review-qlc-nand-arrives |url-status=live |archive-url=https://web.archive.org/web/20231102131136/https://www.anandtech.com/show/13078/the-intel-ssd-660p-ssd-review-qlc-nand-arrives |archive-date=2 November 2023 }}</ref><ref>{{cite web|url=http://www.storagesearch.com/ssdmyths-endurance.html|title=SSD endurance myths and legends articles on StorageSearch.com|website=StorageSearch.com}}</ref><ref name="toms-20181019">{{Cite news |last=Webster |first=Sean |date=19 October 2018 |title=Samsung Announces QLC SSDs And Second-Gen Z-NAND |work=[[Tom's Hardware]] |url=https://www.tomshardware.com/news/samsung-qlc-z-nand-ssd-flash,37945.html |url-status=live |archive-url=https://web.archive.org/web/20231102141850/https://www.tomshardware.com/news/samsung-qlc-z-nand-ssd-flash,37945.html |archive-date=2 November 2023 }}</ref><ref name="pcgamesn-20190108">{{Cite news |last=James |first=Dave |date=8 January 2019 |title=Samsung 860 QVO review: the first QLC SATA SSD, but it can't topple TLC yet |work=PCGamesN |url=https://www.pcgamesn.com/samsung-860-qvo-review-benchmarks-qlc-ssd |url-status=live |archive-url=https://web.archive.org/web/20231121125529/https://www.pcgamesn.com/samsung-860-qvo-review-benchmarks-qlc-ssd |archive-date=21 November 2023 }}</ref><ref name="samsung-20180807">{{Cite press release |date=7 August 2018 |title=Samsung Electronics Starts Mass Production of Industry's First 4-bit Consumer SSD |url=https://news.samsung.com/global/samsung-electronics-starts-mass-production-of-industrys-first-4-bit-consumer-ssd |url-status=live |archive-url=https://web.archive.org/web/20231102132203/https://news.samsung.com/global/samsung-electronics-starts-mass-production-of-industrys-first-4-bit-consumer-ssd |archive-date=2 November 2023 |publisher=[[Samsung]] }}</ref>
|-
| 3D PLC NAND || {{unknown}} || In development by SK Hynix (formerly Intel)<ref name="reuters-20201020">{{Cite news |last1=Jin |first1=Hyunjoo |last2=Nellis |first2=Stephen |last3=Hu |first3=Krystal |last4=Bera |first4=Ayanti |last5=Lee |first5=Joyce |date=20 October 2020 |title=South Korea's SK Hynix to buy Intel's NAND business for $9 billion |editor-last=Coates |editor-first=Stephen |url=https://www.reuters.com/article/us-intel-divestiture-sk-hynix-idUSKBN2742IY |url-status=live |archive-url=https://web.archive.org/web/20231102132619/https://www.reuters.com/article/us-intel-divestiture-sk-hynix-idUSKBN2742IY |archive-date=2 November 2023 |newspaper=[[Reuters]] }}</ref> and [[Kioxia]] (formerly Toshiba Memory).<ref name="auto4" />
|-
| SLC (floating-<br>gate) NOR || 100,000–1,000,000 || Numonyx M58BW (Endurance rating of 100,000 erases per block);<br />[[Spansion]] S29CD016J (Endurance rating of 1,000,000 erases per block)
|-
| MLC (floating-<br>gate) NOR || 100,000 || Numonyx J3 flash
|-
| 3D SLC NOR || >1,000,000 ||
|-
| 3D MLC NOR || 100,000-1,000,000 ||
|}

However, by applying certain algorithms and design paradigms such as [[wear leveling]] and [[Flash over-provisioning|memory over-provisioning]], the endurance of a storage system can be tuned to serve specific requirements.<ref>{{cite web |url=http://www.wdc.com/WDProducts/SSD/whitepapers/en/NAND_Evolution_0812.pdf |title=NAND Evolution and its Effects on Solid State Drive Useable Life |publisher=Western Digital |year=2009 |access-date=22 April 2012 |url-status=dead |archive-url=https://web.archive.org/web/20111112000643/http://www.wdc.com/WDProducts/SSD/whitepapers/en/NAND_Evolution_0812.pdf |archive-date=12 November 2011}}</ref>

In order to compute the longevity of the NAND&nbsp;flash, one must account for the size of the memory chip, the type of memory (e.g. SLC/MLC/TLC), and use pattern. Industrial NAND and server NAND are in demand due to their capacity, longer endurance and reliability in sensitive environments.

As the number of bits per cell increases, performance and life of NAND flash may degrade, increasing random read times to 100μs for TLC NAND which is 4 times the time required in SLC NAND, and twice the time required in MLC NAND, for random reads.<ref name="auto6"/>